Appendix A – DHCP Options (RFC 2132)

A DHCP server can provide optional configurations to the client. Sophos XG Firewall provides support to configure following DHCP Options as defined in RFC 2132.

To set the options, refer to DHCP Management section.

Option Number

Name

Description

Data Type

2

Time offset

Time offset in seconds from UTC

Four-byte numeric value

4

Time servers

N/4 time server addresses

Array of IP addresses

5

Name servers

N/4 IEN-116 server addresses

Array of IP addresses

7

Log servers

N/4 logging server addresses

Array of IP addresses

8

Cookie servers

N/4 quote server addresses

Array of IP addresses

9

LPR servers

N/4 printer server addresses

Array of IP addresses

10

Impress servers

N/4 impress server addresses

Array of IP addresses

11

RLP servers

N/4 RLP server addresses

Array of IP addresses

12

Host name

Hostname string

String

13

Boot file size

Size of boot file in 512 byte chunks

Two-byte numeric Value

14

Merit dump file

Client to dump and name of file to dump to

String

16

Swap server

Swap server addresses

IP address

17

Root path

Path name for root disk

String

18

Extension file

Patch name for more BOOTP info

String

19

IP layer forwarding

Enable or disable IP forwarding

Boolean

20

Src route enabler

Enable or disable source routing

Boolean

22

Maximum DG reassembly size

Maximum datagram reassembly size

Two-byte numeric value

23

Default IP TTL

Default IP time-to-live

One-byte numeric value

24

Path MTU aging timeout

Path MTU aging timeout

Four-byte numeric value

25

MTU plateau

Path MTU plateau table

Array of two-byte numeric values

26

Interface MTU Size

Interface MTU size

Two-byte numeric value

27

All subnets are local

All subnets are local

Boolean

28

Broadcast address

Broadcast address

IP address

29

Perform mask discovery

Perform mask discovery

Boolean

30

Provide mask to others

Provide mask to others

Boolean

31

Perform router discovery

Perform router discovery

Boolean

32

Router solicitation address

Router solicitation address

IP address

34

Trailer encapsulation

Trailer encapsulation

Boolean

35

ARP cache timeout

ARP cache timeout

Four-byte numeric value

36

Ethernet encapsulation

Ethernet encapsulation

Boolean

37

Default TCP TTL

Default TCP TTL

One-byte numeric value

38

TCP keepalive interval

TCP keepalive interval

Four-byte numeric value

39

TCP keepalive garbage

TCP keepalive garbage

Boolean

40

NIS domain name

NIS domain name

String

41

NIS server addresses

NIS server addresses

Array of IP addresses

42

NTP servers addresses

NTP servers addresses

Array of IP addresses

43

Vendor specific information

Vendor specific information

String

45

NetBIOS datagram distribution

NetBIOS datagram distribution

Array of IP addresses

46

NetBIOS node type

NetBIOS node type

One-byte numeric Value

47

NetBIOS scope

NetBIOS scope

String

48

X window font server

X window font server

Array of IP addresses

49

X window display manager

X window display manager

Array of IP addresses

50

Requested IP address

Requested IP address

IP addresses

51

IP address lease time

IP address lease time

Four-byte numeric value

52

Option overload

Overload “sname” or “file”

One-byte numeric value

53

DHCP message type

DHCP message type

One-byte numeric value

55

Parameter Request List

Parameter request list

Array of one-byte numeric values

56

Message

DHCP error message

String

57

DHCP maximum message size

DHCP maximum message size

Two-byte numeric value

58

Renew time value

DHCP renewal (T1) time

Four-byte numeric value

59

Rebinding time value

DHCP rebinding (T2) time

Four-byte numeric value

60

Client identifier

Client identifier

String

61

Client identifier

Client identifier

String

62

Netware/IP domain name

Netware/IP domain name

String

64

NIS+ V3 client domain name

NIS+ V3 client domain name

String

65

NIS+ V3 server address

NIS+ V3 server address

Array of IP addresses

66

TFTP server name

TFTP server name

String

67

Boot file name

Boot file name

String

68

Home agent addresses

Home agent addresses

Array of IP addresses

69

Simple mail server addresses

Simple mail server addresses

Array of IP addresses

70

Post office server addresses

Post office server addresses

Array of IP addresses

71

Network news server addresses

Network news server addresses

Array of IP addresses

72

WWW server addresses

WWW server addresses

Array of IP addresses

73

Finger server addresses

Finger server addresses

Array of IP addresses

74

Chat server addresses

Chat server addresses

Array of IP addresses

75

StreetTalk server addresses

StreetTalk server addresses

Array of IP addresses

76

StreetTalk directory assistance addresses

StreetTalk directory assistance addresses

Array of IP addresses

120

SIP server

The SIP server DHCP option carries a 32-bit (binary) IPv4 address used by the SIP client to locate a SIP server.

Array of IP addresses